Psoriasis is a skin condition that affects about 2 percent of the population. Close to a quarter of a million more people are diagnosed with it every year. It happens when the skin cells start to grow much faster then normal. When that happens, they pile up at the surface and form raised red lesions.

Types of psoriasis

The most common form of psoriasis is called plaque psoriasis. It is characterized by lesions that have a reddened base covered by silvery scales. It most often occurs on the elbows, knees, scalp, lower back, face, palms and the soles of the feet.

The other forms:

* Guttate psoriasis is small dot like lesions. It is often set off by bacterial infections. It most often shows up on the torso, limbs and scalp. * Pustular psoriasis is blisters that can leak. * Inverse psoriasis most often appears in the folds of the skin near the genitals, under the breasts or in the armpits. The outbreak is usually intensely red and inflamed. It will be sensitive to sweating or friction. * Erythrodermic psoriasis is widespread reddening and scaling of the skin that is itchy or painful. It is often preceded by another insult to the skin such as a sunburn or a drug related rash.

Causes

Psoriasis is now believed to be an autoimmune disease. That means the body turns on itself in some way.

It is also believed to have a genetic component. About one third of the people with the condition have relatives with it. that people with psoriasis also report certain things that can trigger outbreaks or make things worse. Triggers can include things such as changes in climate, infections, stress or skin insult. Some drugs used to treat high blood pressure or depression may trigger an outbreak as well.

Psoriasis is not contagious. It is not an infection and someone can't "give it" to someone else.